Crank mechanism



(No Model.) 2 SheetsSheet 1.

G. W. MEIGS 8; E. LEYDEN.

CRANK MECHANISM.

No. 473,942. Patented May 3, 1892.

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551,1 futon W13 I A (No Model.) 2SheetsSheet 2. G. W. MEIGS & E. LEYDEN.

GRANK MECHANISM. No. 473,942. Patented May 3, 1892.

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UNITED STATES PATENT OFFICE.

l r i CRANK MECHANISM.

SPECIFICATION forming part of Lettersilatent No. 473,942, dated May 3,1892.

Application filed July 31, 1891.

To all whom it may concern.-

Be it known that we, GEORGE MEIGs and EDWARD LEYDEN, citizens of theUnited States, residing at Reading, in the county of Berks, State ofPennsylvania, have invented certain Improvements in Crank Mechanisms, ofwhich the following is a specification.

This invention relates particularly to crank mechanisms in which thecrank-shaft is rotated by power strokes applied in one direction onlyand alternately on two cranks-as, for instance,in bicycles or othervelocipedes. In crank mechanisms of this class the length of the crankis necessarily limited, so as to provide a convenient swing for theoperator, and the leverage at which the power is applied iscorrespondingly limited.

The object of our invention is to provide a simple and practicalmechanism by means of which an increased leverage will be secured duringthe power stroke of the operator without increasing the total movementof the swing, and at the same time to give a lead to the beginning ofeach power stroke which will avoid any dead-centers. Heretoforeeccentrically-pivoted levers have been used to operate upon the cranksfor the purpose of increasing the leverage during the power stroke; butthey have not been so arranged as to dispense with the use of slottedconnections, as in the improved construction hereinafter described, thenovel features of which are pointed out in the subjoined claims.

Figure 1 is a side elevation, and Fig. 2 a partial cross-section, of aportion of a bicycle having our improvements applied thereto. Figs. 3,4C, 5, and 6 are diagrams showing the relative positions of the cranksand their opcrating-levers at four different points in the stroke. Fig.7 shows a modified construction, and Figs. 8, 9, 10, and 11 show therelative positions of the operating-levers and the fixed cranks atdifferent points with this arrange ment.

Referring to Figs. 1 and 2, A A represent the front forks, act the forkends, B theaxle, and b the hub, of a bicycle. Crank 0, formed withsupplemental arms 0, are secured to the end of the axle in the usualmanner; but instead of being provided with pedals by means of which toapply rotating power thereto each $eria1No.4=01,296. (No model.)

is operated by means of an eccentrically-pivoted lever D, to which thepower is applied. To each operating-lever D is pivoted at (Z arockingarm D, one endof which is connected at c by a link E with the maincrank-arm C, while its opposite end is connected at f to another link F,pivoted also at f to the supplemental crank-arm c. The lever D is formedwith a circular yoke portion 01, which rides upon the periphery of theprojecting portion a of each forked end, and is retained in placethereon by a plate g and a central screw g. As illustrated, this centerg is forward of the axlecenter and below it. The operation as thusarranged is clearly indicated in Figs. 3, 4, 5, and 6. In these figuresthe cranks C and operating-levers D are indicated by mere lines, thoseon the opposite side of the wheel being dotted. The circle made by thepin (1 around the center 9 may represent the path of theoperating-force.

In Fig. 3 the positions of the parts correspond with those in Fig. 1. Itwill be noticed that the near lever D is sufficiently ahead of thevertical line of the far lever on the opposite end of the axle to permita lead and overcome the dead-center. Itwill be noticed, also, that thecenter of the axle B lies between the pin cl of the lever D and thecenter 9 of the latter, around which the pin cl rotates at a fixeddistance, and that it is therefore acting upon the axle at less than theaverage leverage, though not at the minimum.

In Fig. 4 the axle is represented as having made a quarter-turn, and itwill be seen that the pin (Z has moved over considerably less thanone-quarter of its circular path and that it is now operating at aboutits average leverage, being nearly equally distant from the axle-crank Band center g. The rock-arm D, turning upon the center d, has increasedthe distance between said center and the end 6 of the crank G, thecrank-arm 0 serving as a fulcrum through the medium of the link F.

In Fig. 5 the near lever D is in the vertical dependent position inwhich the far lever is shown to be in Figs. 1 and 3,while the far leverhas in its turn assumed the position of lead. It will be noticed thatthis has been accomplished by reversing the angle of the levers withrelation to each other, the far 1ever turning sufficiently faster togain the position of lead while the near lever has been acting atgreatly-increased leverage.

In Fig. 6 the near lever is on its idle return movement, the rotarypower being applied to the opposite crank and its leverage is quicklyreduced to the minimum. In the last quarter-turn, which brings it backto the position of lead shown in Figs. 1 and 3, the point of laterportion of the power-stroke, and though we have shown the greaterleverage in the later portion of the stroke, this may be readilychanged, if desired, by placing the center g,

above instead of below the crank-center.

' In the modified construction shown in Fig.

7 the arrangement has been changed so as to, secure the greater leverageduring the earlier The rocking arm D" portion of the stroke. has alsobeen dispensed with and substantially the same effect produced as withthe former construction, as will be seen upon inspection of the diagram,Figs. 8, 9, 10, and 11, corresponding with Figs. 3, 4, 5, and 6 of theprevious construction.

In either of the constructions shown it will be noticed that at the endof a power-stroke upon one lever the opposite lever has been It iscomgiven an amount of lead, which throws it somewhat past thedead-center and into position to be at once operated upon in the samedirection, thus permitting'a continuous exercise of effectiverotating-power upon one lever or the other. There being no slidingconnections between the parts, the bad elfect of dirt which wouldotherwise tend to make the mechanism practically unsatisfactory is notfelt.

Having thus fully described our invention,

- 'we do not limit ourselves to the particular constructionsspecifically set forth; but

What we claim is- 1. In a crank mechanism for velocipedes or equivalentpurposes, the combination, with cranks fixed to the rotary shaft, ofeccentricall y-pivoted rotary operating-levers and links pivotallyconnected at opposite ends to said levers and cranks, respectively,substantially as and for the purpose set forth.

2. In a crank mechanism for velocipedes or equivalent purposes, thecombination, with cranks fixed to the rotary shaft, ofeccentrically-pivoted rotary operating-levers, rocking arms pivoted tosaid operating-levers, and links F and F, connecting the opposite endsof said rocking-arms to the fixed cranks, substantially as and for thepurpose set forth.

In testimony whereof we affix our signatures in presence of twowitnesses.

GEORGE W. MEIGS. EDWARD LEYDEN.

Witnesses:

JAMES A. OREILLY, H. A. ZIEBER.

